BREEDING POULTRY FOR EGG PRODUCTION. I5I 



111 Other words it would be expected on the hypothesis set 

 forth, and in so far hypothesis and actual fact are in precise 

 accord, that the record of egg production in and of itself alone 

 is not a criterion of particular signficance in selecting females 

 for breeding for improved egg production in the flock. It ap- 

 pears to be of vastly more importance to know the genotype 

 of the hne to which the individual belongs. This idea is already 

 perfectly familiar to the successful breeders of poultry for 

 fancy points. What is here called "blood line" they usually call 

 a "strain." 



In 1907-08 a plan of breeding designed to test the general 

 hypothesis above set forth was put into operation. A statement 

 of a portion of the results which have been obtained to date is 

 given in Part IV. This part of the bulletin is a reprint of an 

 address given before the American Society of Naturalists in 

 December, 1910. It seems advisable to reprint it in entirety 

 here, though to do so involves some repetition of points already 

 brought out in this bulletin. For this the author would ask the 

 reader's pardon. 



PART IV. 



Inheritance oe Fecundity in the Domestic Fowe.* 



There are under discussion at the present time two general 

 views regarding certain fundamental points in heredity. Each 

 of these points of view has its zealous adherents. On the one 

 hand is what may be designated the "statistical" concept of in- 

 heritance, and on the other hand, the concept of genotypes. By 

 the "statistical" concept of inheritance is meant that point of 

 view which assumes, either by direct assertion or by implica- 

 tion, that all variations are of equal hereditary significance and 

 consequently may be treated statistically as a homogeneous mass, 



* Papers from the Biological Laboratory of the Maine Experiment 

 Station, No. 25. This paper was read at the meeting of the American 

 Society of Naturalists at Ithaca, December, 1910. It was first published 

 in the American Naturalist, Vol. XLV, pp. 321-345, June, 191 1, and is 

 here reprinted without change except that the numbers of the figures 

 are here changed to accord with the preceding figures in this bulletin. 

 Figures i to 5 inclusive of the original publication become figs. 80 to 84 

 respectively in this reprint. 



